1. Field of the Invention
The present invention relates generally to a system and method for controlling the travel of a hybrid electric vehicle in an emergency, and, more particularly, to a system and method for controlling the travel of a hybrid electric vehicle in an emergency, which restricts the vehicle speed and maximum torque of a vehicle when an abnormality occurs in a low voltage Direct Current-to-Direct Current (DC-DC) converter and the voltage of a low voltage battery deviates from the operational voltage range of a braking device.
2. Description of the Related Art
Generally, a Hybrid Electric Vehicle (HEV) uses a high voltage of 110V or greater when the driving force of a motor during sudden acceleration is applied and charges when the vehicle is braking. When viewed on the basis of electric power efficiency or new construction of the electric/electronic system of such a hybrid electric vehicle, it is advantageous to increase the power of the system based on high voltage power when high voltage power exists. However, there is a risk of electric shock exists and requires a large amount of time and effort and unnecessary development work to change the existing systems in place.
One such design has tried to address this problem by using two types of batteries at the same time, that is, a main battery for high voltage which uses a main voltage of 250V or more and a subsidiary battery for a general vehicle which uses a voltage of 12V. The main battery for high voltage supplies a specific amount of power to a driving system, air conditioner, and heater in the hybrid electric vehicle. The subsidiary battery which supplies a voltage of 12V supplies power to various types of electric/electronic assemblies as in the system of a general commercial vehicle. In particular, such a hybrid electric vehicle uses a subsidiary battery having a voltage of 12V. When the subsidiary's power battery is insufficient, the subsidiary battery is charged using a Low voltage DC-DC Converter (LDC) for converting high voltage into low voltage.
However, when problems occur in a low voltage DC-DC converter or errors occur in communications with the low voltage DC-DC converter, the voltage of a subsidiary battery continuously drops, so that electric/electronic assemblies may not normally operate or malfunctions may occur. In particular, when power is not smoothly supplied to a braking device, the braking performance of a vehicle is seriously deteriorated, thereby increasing the risk of an accident.